1. Field of the Invention
The present invention relates to a method for managing clients of a network storage system efficiently.
2. Description of Related Art
In recent years, storages have been expanded in capacity and reduced in price. Especially, with the progress of the techniques related to magnetic disks for realizing high recording density, it is about to be realized that one housing of storage comes to have a capacity of several tens of terabytes, which has been impossible so far.
On the other hand, networks have also been enhanced. In recent years, there have appeared even low priced networks that realize transfer rates of one gigabits/sec to 10 gigabits/sec. Conventional networks have been limited in transfer rate just within 10 megabits/sec to 100 megabits/sec, so that it has been difficult to build up an efficient system for transferring mass of data; the conventional system transfer performance is often degraded significantly when many users attempt to access a network concurrently. However, it cannot be impossible to build up a system that meets such requirements with use of a network of which transfer rate is one gigabits/sec to 10 gigabits/sec.
Under such circumstances, much attention is paid now to a network storage system, which is connected to a network and the users (clients) of the system are permitted to access the data stored in a common storage through the network. For example, JP-A No. 196961/2002 discloses a configuration of such a network storage system. In that system, a network connecting part, a server processing part, and a disk unit are disposed in the same housing. Each client accesses the common storage through the network using a communication method provided from the server, thereby the clients can input/output data stored in the server connected to the network as if the data is stored in itself.
One of the problems that must be solved with respect to such network storage systems that are getting to be expanded in scale is how to manage the storages. As a storage is expanded in scale, the method for managing the performance and its clients comes to be complicated. For example, JP-A No. 132455/2002 discloses such a method for managing a large-scale storage. According to the method, a large-scale memory unit for caching clients' data is connected to a subject network. This method is often employed to solve problems that might occur when in realizing of large scale high performance storages. On the other hand, JP-A No. 67187/2001 discloses a method for managing clients. The method enables a few managers to manage clients of storages disposed in a single housing.
A small scale storage can be managed by a few managers, since the number of clients is small. In the case of a large scale magnetic disk, however, the total capacity of one storage housing often becomes several tens of terabytes. In such a case, it is expected that the number of clients becomes several thousands to several tens of thousands. Management of clients mentioned here means allocating a storage area to each client and setting an access privilege for the client with respect to the allocated area. For example, each client comes to have a network (IP) address, a disk area name (/user/a), an access privilege (to read/write data from/to the allocated disk area), etc. set for the client. If such a client moves, the setting of the client must be updated.